A conventional assembly for heavy-duty trucks used in on-road and off-road service includes a tandem axle assembly. Tandem axle assemblies commonly employ inter-axle differentials to divide power between the forward and rear axle assemblies. The forward and rear axle assemblies each include a pair of axle half shafts extending therefrom on which one or more wheels of a vehicle are mounted. The inter-axle differential enables speed differences between the drive axles, e.g., to allow torque balance between the drive axles during the vehicle cornering, to compensate for tire size differences, etc.
Inter-axle differential gear mechanisms, or differentials, are well-known devices. Inter-axle differentials can include a pair of side gears in mesh with, and driven by, the pinion gears. One side gear is used to drive the pinion gear of the forward axle assembly wheel differential. The other side gear is coupled to an output shaft that extends outwardly from the forward axle assembly housing and drives the intermediate drive shaft assembly and, indirectly, the pinion gear of the rear axle assembly wheel differential.
It may be necessary to lock the inter-axle differential to prevent power from being delivered to a wheel that has lost traction during hazardous driving conditions. In conventional inter-axle differentials, a locking clutch member is disposed about the input shaft and can be shifted into engagement with a second clutch member typically defined by one of the side gears to lock the inter-axle differential.
Although many limited slip differential devices are known, there is a need for an invention that can passively limit inter-axle differential without intervention from the operator, limiting damage caused by improper lock out clutch engagement. The deletion of the lock out clutch may also reduce the overall cost as well.